The goal of this proposal is to investigate the mechanism by which learning and adaptation can alter the orientation tuning of neurons in primary visual cortex. Learning to discriminate small changes in the orientation of a bar has been shown to sharpen the orientation tuning curves of cells whose preferred orientation is near the bar's orientation, while adapting to an oriented grating has been shown to broaden the tuning curves and shift the tuning curve peaks of cells whose preferred orientation is near the adapted orientation. Understanding these phenomena will contribute to our understanding of neuronal processing, which will play a critical role in both clinical and basic neuroscience in the twenty-first century. The goal of Specific Aim 1 is to determine whether modifying intracortical connections is necessary and sufficient for simulating learning and adaptation in a network where the feed-forward input from the lateral geniculate nucleus is sharply tuned for orientation, and will be accomplished by building on past modeling efforts. The goal of Specific Aim 2 is to experimentally test the prediction that adaptation in alert, non-anesthetized subjects causes physiological changes that are a transient version of the changes seen in learning.